Core type reel drive



R. R. BAKER 2,508,135

CORE TYPE REEL DRIVE Filed Feb. 24, 1947 WITNESSES:

INVENTOR Pea fEBQX/f 'BY I 611v)- W ATT RNEY Patented May 16, 1950 CORETYPE REEL DRIVE Rest R. Baker, Pittsburgh, Pa., assignor to WestinghouseElectric Corporation, East Pittsburgh, Pa., a corporation ofPennsylvania Application February 24, 1947, Serial No. 730,501

7 Claims.

My invention relates to electric drives for winding yarn, thread,strips, or sheets of paper, textile, metal, or other material onto oroff a coretype reel.

For the operation of core-type reels, it is frequently necessary ordesirable to maintain a constant tension in the material being reeled.In fabricating machinery, it is usually required to move the material tobe reeled at a substantially constant linear traveling speed. In orderto meet this requirement, the equipment for driving the core-type reelmust necessarily vary the rotational speed of the core due to the factthat the diameter of the reeled material changes progressively duringthe reeling operation. To accomplish a proper variation in rotationalspeed, the core drives are frequently equipped with slip-belt drives.Such drives are designed to rotate the empty core at the correct speedand to slip the amount necessary for accommodating the larger rolldiameters. In order to maintain constant tension in the material beingreeled,-it is also necessary to increase the torque on the core driveshaft as the roll diameter increases.

There are electric drives to replace the slipbelt type of drive for theabove-mentioned purposes. These electric drives have a reel drive motorof the direct-current type whose field is separately excited by means ofa current regulator. The electric drive functions to maintain, at aparticular operating speed and voltage, a constant current input to thereel motor. Constant current input at constant voltage is equivalent toconstant horse-power input which results in substantially constanttension in the material being reeled. As the diameter of the roll ofmaterial on the core increases, the current regulator increases thefield excitation of the reel motor, and at maximum diameter of the roll,the motor has a field excitation equivalent to the ratio of maximumdiameter to minimum diameter times minimum excitation. The torquedeveloped at constant current will then be in the direct ratio of themaximum and minimum diameters, and the operating speed is then inverselyproportional to the diameters.

It is an object of my invention to provide an electric drive forcore-type reeling equipment which is capable of maintaining the materialto be reeled under substantially constant tension, while requiring forthis performance a considerably reduced amount of equipment as comparedwith the above-mentioned electric drives heretofore known for thispurpose.

In order to achieve these objects, and in accordance with one of thefeatures of my invention, I provide a core-type reel drive with adirect-current drive motor of the series type which is so rated that itoperates along the un-- saturated and substantially straight portion ofits magnetic characteristic; and I further provide the armature andseries field circuit of thismotor with electric calibrating means, suchas an impedance or a source of bucking voltage, which adjusts the IRdrop in this armature circuit relative to the energizing voltageimpressed on a motor so that the following conditions are satisfied.

In order to maintain constant tension in the strip, at a single stripspeed, the torque of the motor must vary directly as the roll diameterwhile the speed of the motor must vary inversely as the diameter. Thespeed of a series motor may be adjusted by varying the IR drop in thearmature circuit. From the required relationships, given above, betweentorque, speed, and diameter, and from the well known speed and torqueequations of an unsaturated series motor, it can be shown that the speedand torque of such a motor will vary so as to maintain constant tensionprovided that the IR. drop in the armature circuit is so adjusted thatthe following equation is substantially satisfied.

wherein IR represents the IR. drop in the armature circuit; E, thevoltage energizing the cir-" cuit; D2, the maximum diameter of the rollof material reeled up on the core; and D1, the minimum diameter of thatroll which is usually identical with the diameter of the reel core.

It can be seen that, by the use of the above equation, it is possible toselect a single value of R that will satisfy the requirements forconstant tension at two roll diameters. It has been found that a valueof B so selected will cause operation at substantially constant tensionover a wide variation of roll diameters.

If the fabricating machinery, that passes the material toward the reel,operates at constant speed, the energizing voltage for the drive motoris also constant, and hence may be derived from any suitable source ofconstant direct-current voltage. However, if the fabricating machineryassociated with the reel is designed for operation at adjustable speed,then the voltage for energizing the motor must change in proportion tothe change in the linear traveling speed of the material to be reeled.In order to obtain the proper variation in voltage, and in accordancewith another feature of the invention, this voltage may be generated bya direct-current generator whose armature is connected to thefabricating machinery in order to rotate at a speed proportional to thetraveling speed, of the material.

The above-mentioned and other objects and features of my invention willbe apparent from the following description of the embodimentsillustrated in the drawing, in which:

Figure 1 represents diagrammatically a fabricating machine and reeldrive in conjunction. with the essential circuits and devices of anelectrio reel drive according to the invention,

Fig. 2 is an explanatory speed torque diagram relating to the electricsystems shown in Figs. 1 and 3, and

Fig. 3 represents diagrammatically a modified form of drive according tothe invention.

According to Figure 1, the material I passes through fabricatingmachinery 2, here schematically represented as a calender, and passesfrom this machinery onto the core 3 of winding equipment. The core 3' isdriven by a suitable mechanical transmission 4 from the armature 5 of adirect-current series-type motor M whose series field is denoted by 6.The transmission, here shown as a shaft connection, may include thereduction gears usually present in such equipment. The motor circuit isenergized from the armature I of a. generator G whose field winding 8 isseparately excited from a constant voltage source 93, preferably througha calibrating rheostat iii. The adjustment of rheostat Ii need not hechanged during the normal operation of the drive system. The generatorarmature I is mechanically connected tothe machinery 2 by means of atransmission I I, here schematically represented bya shaft connection.This transmission, as shown, is also in mechanical connection with amotor I2, or other prime mover, for operating the machinery 2 at thedesired speed. A speedadjusting device for the motor I2 is schematicallyexemplified by a rheostat I 3. An adjustable rheostat I 4 is connectedin the motor or loadcircuit in series relation to the armatures 5 and 1and the motor field winding. 6. The slide contact of rheostat I4 isconnected, as schematically shown at I5, with the adjustable member ofthe speed control device it so that the setting of rheostat I54 ischanged together with. change in the speed adjustment of the device I3.

In the coordinate diagram shown in Fig. 2, a speed torque characteristicis denoted.- by Hi as being representative of the speed torque relationrequired for the transmission 4 in order to maintain the material Iunder constant tension for any singular traveling speed of the materialI. The required ideal speed torque curve I5 has a hyperbolic form. If,in the drive system according to Figure 1, the motor M operates withinthe unsaturated and approximately straight region of its magneticcharacteristic, and if the resistance value of rheostat I4 is soadjusted by the appertaining slide contact that, at the justmentionedsingular speed, the IR, drop including the circuit conductors, therheostat H, the armatures I and 5 and the field winding 6 bears therelationship to the applied voltage indicated by the above-givenequation, then the reel performance will closely match the speed torquerequirement represented by the curve 16 in Fig. 2. That is, under thejust-mentioned conditions, the actual driving effort exerted by themotor M on the transmission 3 corresponds approximately to the speedtorque characteristic IT in Fig. 2. The percentage of reeling error isvery small and negligible for most cases of application, especially ifthe actual performance characteristic Ii is made to intersect the idealcharacteristic Iii in such a manner that the remaining errors areapproximately equally distributed between plus and minus values.

l1" the speed of the processing or fabricating machinery, and hence thelinear traveling speed of the material, changed, the voltage E impressedon the load circuit of the series motor is likewise changed and itfollows from the abovegiven equation that then the rheostat it must alsobe adjusted in order to calibrate the IR drop in the motor generatorcircuit to the new value required for the increased voltage. It ispreferred to effect such a recalibration automatically by thetransmission between the rheostat M and the speed-adjusting device I3represented in Fig. l at IE. Consequently, when the speedadjustingdevice I3 is set for a higher running speed of the machinery 2, therheostat I4 is simultaneously adjusted for a correspondingly increasedIR drop in the armature circuit. As a omit, the ratio of voltage to IRdrop remains in proper relation to the reeling diameters to securesubstantially constant tension in the material over the available rangeof traveling speeds.

The embodiment shown in Fig. 3 differs from the above-described drivesystem of Fig. 1, substantially by the fact that a bucking generator isused in the motor circuit in order to provide for the proper calibrationof the voltage to IR drop relation in this circuit.

According to Fig. 3, the material 2! passes from fabricating machinery22 onto the core 23 of the reel drive. The core is driven through atransmission 24 from the armature 25 of the reel motor M whose fieldwinding "26 is connected in series with the armature 25 across thearmature 2': of the generator G. The field winding 28 of generator G isexcited from constant voltage mains 29 through a calibrating rheostat 30of fixed adjustment during normal operation of the system. The generatorarmature 21 is mechanically connected to the machinery 22 and driventogether therewith by a motor 32 whose speed is adjustable by means of arheostat 33 or other speed-controlling device.

Series connected in the circuit of motor M, is the armature 34 of abucking generator B. Armature 34 is driven at constant speed by anauxiliary motor 35. The field winding 36 of generator B is also seriesconnected in the circuit of motor M so that the voltage generated in thearmature 34 varies in proportion to the current flowing in the motorcircuit. Field winding 35 is connected with a field rheostat 31 whoseslide contact is ganged together, by a transmission shown at 38-, withthe speed-adjusting device 33- of the motor 32.

The voltage superimposed on the motor circuit is so rated by properadjustment of the field rheostat 31 that the IR drop in the motorcircuit, including the armatures 25, 21, 34 and the field windings 26,36, with the rheostat 31, has the above-given relation to the energizingvoltage E generated across the armature 21. Under these conditions, thesystem according to Fig. 3 functions similar to that of Fig. 1 inmaintaining the tension of the material being reeled at a substantiallyconstant value. The system of Fig. 3,

though somewhat more intricate than the one shown in Fig. 1, has theadvantage that it permits' introducing the energy, or part of theenergy, dissipated in the rheostat M of Fig. 1 back into the source ofthe electric power supply driving the motor 35.

Systems according to my invention, as exemplified by the above-describedembodiments, may be provided with customary protective devices andaccessories, for instance with protective contact means which stop thedrive or prevent the reel from running at excessive speed in a case of abreak in the material. Such and other modifications of my invention, aswell as alterations and changes in the elements composing such drivesystems, will be obvious to those skilled in the art, and it shouldtherefore be understood that the invention, as defined by the annexedclaims, permits of embodiments other than those specifically illustratedand described in detail in the foregoing.

' I claim as my invention:

1. A core-type reel drive for maintaining substantially constant tensionin the material to be reeled, comprising a direct-current reel motorhaving an armature and a series field winding and being rated to operatealong the substantially straight unsaturated portion of its magneticcharacteristic over the range of desired speeds, circuit means forproviding energizing voltage proportional to the traveling speed of thematerial, a load circuit connected across said circuit means andincluding in series-connection said armature and said field winding, anda resistor series-connected in said circuit and rated to establish insaid circuit an IR drop substantially in accordance with the equationwherein IR is said IR drop, E said energizing voltage and the ratio ofmaximum to minimum diameters of the reel to be driven by said motor.

2. A core-type reel drive for maintaining substantially constant tensionin the material to be reeled, comprising a direct-current reel motorhaving an armature and a series field winding and being rated to operatealong the substantially straight unsaturated portion of its magneticcharacteristic over the range of desired speeds, circuit means forproviding energizing voltage proportional to the traveling speed of thematerial, a load circuit connected across said circuit means andincluding in series-connection said armature and said field winding, anda series bucking generator connected in said circuit and having a linearrelationship of its bucking voltage to the current in said circuit so asto maintain in said circuit an IR drop substantially in accordance withthe equation wherein IR. is said IR drop, E said energizing voltage andthe ratio of maximum to minimum diameters of the reel to be driven bysaid motor.

3. A core-type reel drive for maintaining substantially constant tensionin the material to be reeled, comprising drive means havingspeed-adjusting means for controlling the linear traveling speed of thematerial, circuit means associated: with said drive means to provide avoltage pro-- portional to said speed, a direct-current windermotor forreeling the material having an armature and a series field winding andbeing rated to operate along the substantially straight unsaturatedportion of its magnetic characteristic over the range of desired reelingspeeds, a circuit connected to said circuit means to be energized bysaid voltage and including in series said armature and said fieldwinding, an adjustable control member series-connected in said circuitand connected with said speed-adjusting means so as to be adjustedtogether with the latter in order to maintain the IR drop in saidcircuit, regardless of the setting of said speed-adjusting means,substantially in accordance with the equation wherein IR is said IRdrop, E said energizing voltage and the ratio of maximum to minimumdiameters of the reel to be driven by said motor.

4. A core-type reel drive for maintaining substantially constant tensionin the material to be reeled, comprising drive means havingspeed-adjusting means for controlling the linear traveling speed of thematerial, a generator mechanically connected to said drive means forproviding a voltage proportional to said speed, a direct-current windermotor for reeling the material having an armature and a series fieldwinding and being rated to operate along the substantially straightunsaturated portion of its magnetic characteristic over the range ofdesired reeling speeds, a circuit including in series-connection saidgenerator, said armature and said field winding, an adjustable rheostatseries-connected in said circuit.

5. A core-type reel drive for maintaining substantially constant tensionin the material to be reeled, comprising drive means havingspeed-adjusting means for controlling the linear traveling speed of thematerial, a generator mechanically connected to said drive means forproviding a voltage proportional to said speed, a direct-current windermotor for reeling the material having an armature nd a series fieldwinding and being rated to operate along the substantially straightunsaturated portion of its magnetic characteristic over the range ofdesired reeling speeds, a circuit including in series-connection saidgenerator, said armature and said field windwherein IR is said IR drop,E said energizing voltage and the ratio of maximum to minimum diametersof the reel to be driven by said motor.

6. With fabricating machinery for material having an adjustable speeddrive for said machinery, the'combination of a winder drive for reelingsaid material comprising a direct-current generator having an armaturemechanically connected to said machineri to be driven at proportionalspeed and having a separately excited field winding for constantexcitation to provide a voltage substantially proportional to saidspeed, a direct-current motor having an armature and a field winding, anadjustable rheostat, a circuit including in series relation saidgenerator armature, motor armature, motor field winding and rheostat,said rheostat having its resistance rated to adjust the IR drop in saidcircuit substantially in accordance with the equation connecting saidrheostat with said machinery drive so as to calibrate said rheostat formaintaining said equation when said machinery drive is set for adifferent speed.

'7. With fabricating machinery for material having an adjustable speeddrive for said machinery, the combination of a Winder drive for reelingsaid material comprising a direct-current generator having an armaturemechanically connected to said machinery to be driven at proportionalspeed and having a separately excited field winding for constantexcitation to provide 9, voltage substantially proportional to saidspeed, a direct-current motor having an armature and a field winding, acircuit including in series said generator armature, said motor armatureand said motor field winding, a bucking generatorm'il wherein IR is saidIR drop, E said energizing voltage and the ratio of maximum to minimumdiameters of the reel to be driven by said motor.

REST R. BAKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,801,598 Evans Apr. 21, 19311,987,670 Drake et a1 Jan. 15, 1935

